Can't run Speed Tracer in Chrome 5 dev

I'd like to use the Speed Tracer extension for Chrome 5 dev and it needs the --enable-extension-timeline-api.

I've set the option ins GoogleChromePortable.ini located in \PortableApps\GoogleChromePortableDev\Other\Source:

[GoogleChromePortable]
Google ChromeDirectory=App\Chrome-bin
ProfileDirectory=Data\profile
SettingsDirectory=Data\settings
AdditionalParameters=--enable-extension-timeline-api

Google ChromeExecutable=chrome.exe
WaitForProgram=true
DisableSplashScreen=false
RunLocally=false
CacheInTemp=true

ImportJava=false
UsePAMLanguage=true
PortablePasswords=false
EncryptPortablePasswords=true

Chrome is still loading without this parameter and I can't run Speed Tracer.
Any ideas?